Multiple layer insulation cover

ABSTRACT

A multiple layer insulation cover for preventing heat loss in, for example, a greenhouse, is disclosed. The cover is comprised of spaced layers of thin foil covered fabric separated from each other by air spaces. The spacing is accomplished by the inflation of spaced air bladders which are integrally formed in the cover and to which the layers of the cover are secured. The bladders are inflated after the cover has been deployed in its intended use to separate the layers of the foil material. The sizes of the material layers are selected to compensate for sagging across the width of the cover so that the desired spacing is uniformly maintained when the cover has been deployed. The bladders are deflated as the cover is stored thereby expediting the storage process and reducing the amount of storage space required.

The Government has rights in this invention pursuant to USDA Grant No.58-7B30-8-18 awarded through the U.S. Department of Energy.

FIELD OF THE INVENTION

The present invention is directed generally to an insulation cover,which is deployed and stored as desired. More specifically, the presentinvention is directed to a multiple layer insulation cover for agreenhouse. More specifically, the present invention is directed to afour layer insulation cover for a greenhouse in which the layers arespaced from each other by inflatable air bladders. The spaced layers ofmaterial in the insulation cover are preferably comprised of a metalfoil such as aluminum which is secured to a polyester scrim. Spaced airbladders are incorporated in the cover and these bladders are inflatedonce the cover has been deployed to space the layers. The cover isstored on a suitably driven roll and as the cover is retracted onto theroll, the air bladders are deflated.

In use as a greenhouse insulation cover, the multiple layer cover isstored on a roll above the level of the growth in the greenhouse. Whenthe sun sets in the evening, or at any other time such as an overcastday, the cover is deployed to prevent heat loss through the roof of thegreenhouse. The air bladders, which are inflated after the cover hasbeen deployed, act to separate the layers of the cover, thus created airspaces between the layers to form an effective insulation cover whichretains heat in the greenhouse.

DESCRIPTION OF THE PRIOR ART

The rising costs of fuel have created a severe problem for thegreenhouse industry. The structure of the greenhouse, which allowsmaximum sunlight during the day, also allows a great deal of heat toescape during the evening. Approximately 10,000 acres are presentlyunder glass in the United States; and as the costs of fuel oil and othersources of energy increase rapidly, the greenhouse owner is quicklybeing pushed to the point where he cannot continue in operation.

The problem of heat loss in greenhouses has been recognized and the useof covers for greenhouses is known generally in the prior art. In oneform, these covers are flexible transparent sheets which are secured tothe roof of the greenhouse on the exterior thereof and are inflated bysuitable means to provide an air space between the cover and the roof.Another device for cutting down on heat loss during the night is the useof insulating panels of materials such as expanded foams or the like.These panels are either cut to shape and put up in the evening and takendown in the morning or are arranged in a manner similar to venetianblinds so that they are opened during the day and closed at night.

A recent attempt at reducing greenhouse heat loss is shown in U.S. Pat.No. 4,064,648 to Charles C. Cary. The Cary patent is directed to aninsulation system for greenhouses and the like and is comprised of aflexible sheet of material which is wound around a roll, is deployed atnight, and is stored during the day. Rolls of this material are placedlongitudinally along the length of the greenhouse and are unrolledacross the greenhouse. The edges of the flexible sheet are disposedgenerally in a channel or box at either side and a cogged wheel assemblymay be used to deploy the sheet. The Cary patent also discloses a systemfor opening the cover in response to snow accumulation on the roof ofthe greenhouse.

The use of various heat retaining structures and elements is also knowngenerally in conjunction with building windows, swimming pools, andother such facilities. These structures are often in the form of solidpanels which can be moved from a storage location to a use location bysome suitable means. Alternatively, these structures may be a flexiblesheet of material which is stretched or otherwise secured across thearea to be protected.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a multiple layerinsulation cover.

Another object of the present invention is to provide a multiple layerinsulation cover in which the layers are maintained in spaced array byinflatable air bladders.

A further object of the present invention is to provide an insulationcover for use in a greenhouse.

Still another object of the present invention is to provide aninsulation cover having a positive edge seal between the cover and asupport track.

Yet a further object of the present invention is to provide a coverwhich is effective to reduce heat losses by convection, conduction, andradiation.

As will be set forth in greater detail in a description of a preferredembodiment, as set forth hereinafter, the multiple layer insulationcover in accordance with the present invention is comprised generally offour layers of metal foil secured to polyester scrim. The four layersare joined, along their longitudinal sides to inflatable air bladders.As the bladders are inflated, the multiple layers are caused to separatethereby creating air spaces between each layer. The longitudinal edgesof the cover terminate in generally T-shaped strips which cooperate withsupports such as PVC piping or the like having an axially extendingslot. The top of the T-shaped strip is placed within the support pipingwith the leg of the T extending out through the slot in the pipe.Suitably spaced reels, driven by electric motors or the like, are placedat either end of the area in which the cover is to be deployed to movethe cover between its stored and deployed positions.

In contrast with known greenhouse insulation covers which are in theform of solid sheets or panels, the multiple layer insulation cover inaccordance with the present invention is flexible and can be stored on aroll when not in use. This facilitates the deployment of the cover in ashort period of time with little effort. Furthermore, the stored covertakes a minimum amount of space, thus when used in a greenhouse,allowing full utilization of the space within the greenhouse.

As was discussed previously, a flexible greenhouse cover is showngenerally in U.S. Pat. No. 4,064,648 to Cary. This patent shows a singleor double layer cover with, in the double layer cover, the two layersbeing separated over their entire areas by air pressure. In contrast,the multiple layer insulation cover in accordance with the presentinvention is formed of spaced layers with the spacing being accomplishedby inflatable air bladders along the edges of the cover. Theseinflatable bladders allow the equal spacing of the four layers. Spacingof more than two layers could not be obtained with the Cary deviceunless the pressures between the layers were accurately controlled. Byinflating only elongated tubes instead of the total area between thecover layers, the size of the blowers required can be reduced, thusreducing initial cost and operating expense. Additionally, the tubes aremore rapidly inflated and deflated to facilitate deployment and storageof the cover.

In the cover set forth in the Cary patent, there are provided aplurality of separate covers, each of which extends transversely acrossthe greenhouse. Contrastingly, in the multiple layer insulation cover ofthe present invention, the cover extends longitudinally along the lengthof the greenhouse. This type of deployment greatly reduces the length ofthe edges that must be sealed to prevent escape of heated air. Eachlongitudinal edge of the cover of the present invention ends in aT-shaped strip which rides in a support such as a hollow tube having anaxially extending slot. The cooperation between the top of the T-shapedelement and the hollow support, forms a positive seal which preventsescape of heated air. The short transverse ends of the cover can besealed by any suitable means and this is a small area to seal incontrast to the longitudinal edges.

The material used to construct the multiple layer insulation cover inaccordance with the present invention is preferably a flexible metalfoil adhered to a polyester scrim. This material is readily availablecommercially, is easy to work with, is durable, and is not expensive.Thus, the cover which is produced is also long wearing and durable. Itsinitial cost and upkeep costs are low in comparison to the cost ofheating fuels so that the costs of installing and operating an assemblyusing the multiple layer insulation cover of the present invention areattractive to the owner of a greenhouse or the like.

Since the materials used in the construction of the cover are durableand highly flexible, the cover can be rolled on a storage roller andwill require little space. Repeated deployment and storage of themultiple layer insulation cover, as would be required in day to dayusage, will not cause the materials to wear out rapidly, thus assuringthe owner of the facility in which the cover is used of having aneffective, durable and trouble free cover which is easily and rapidlydeployable to prevent heat losses and to thereby substantially reducefuel costs in a greenhouse, warehouse, or any similar area having heatloss problems.

BRIEF DESCRIPTION OF THE DRAWINGS

While the novel features of the multiple layer insulation cover inaccordance with the present invention are set forth with particularityin the appended claims, a full and complete understanding of the presentinvention may be had by referring to the description of a preferredembodiment as set forth hereinafter and as seen in the accompanyingdrawings in which:

FIG. 1 is a schematic perspective view, partly in section, and withportions removed for clarity of a multiple layer insulation cover inaccordance with the present invention, the cover being deployed in agreenhouse; and

FIG. 2 is a perspective view, partly in section, showing a portion of amultiple layer insulation cover in accordance with the presentinvention.

DESCRIPTION OF A PREFERRED EMBODIMENT

Turning initially to FIG. 1, there may be seen generally at 10, amultiple layer insulation cover in accordance with the presentinvention. In the preferred embodiment, cover 10 is shown deployed in aconventional greenhouse, generally at 12. While the cover 10 willhereinafter be discussed and described in conjunction with a greenhouse,it is to be understood that the invention is not limited to such use.The multiple layer insulation cover in accordance with the presentinvention can be used advantageously in any area where it is desired toreduce heat loss. By way of example, the cover could be utilized in awarehouse to substantially reduce heat loss through a poorly insulatedroof. Similarly, in a passive solar house with south facing windows, thecover in accordance with the present invention could be used to coverthe windows when there is no sunlight thereby substantially reducingheat loss. Accordingly, while the multiple layer insulation cover willbe hereinafter described in use in a greenhouse, its uses are not solimited.

As may be seen in FIG. 1, greenhouse 12 is of conventional constructionand has a plurality of transparent panels 14 which are supported byspaced uprights 16 and roof trusses 18 to form greenhouse structure 12which has spaced longitudinally extending walls 20 and 22 and a peakedroof 24. One end wall 26 of greenhouse 12 may be seen at the right ofFIG. 1 and it will be understood that the greenhouse would be closedwith a second end wall which, for clarity, is not shown. It will also beunderstood that greenhouse 12 could be shaped generally as ahemicylinder or other known shape. Greenhouse 12 is also provided with aplurality of spaced benches or supports 28 upon which the plants beinggrown are placed.

Multiple layer insulation cover 10 is comprised, as may be seen in FIG.1, of four spaced layers 30, 32, 34, and 36, which extend between theside walls 20 and 22 of greenhouse 12 and which terminate in inflatableair bladders 38 and 40, which, as will be described in greater detailhereinafter serve to separate the layers 30-36 when inflated. The cover10 extends longitudinally along the length of the greenhouse 12 and issecured to the walls 20 and 22 by support tubes 42 which are connectedto the spaced uprights 16, as will be described hereinafter. A storagereel 44 is shown supported at the first end 26 of greenhouse 12 byconventional means. Reel 44 extends transversely across the greenhouseside walls 20 and 22 and is rotatable by a suitable power source such asan electric motor 46 which transmits power to reel 44 through a drivebelt 48 or the like. It will be understood that there is also provided acorresponding deployment reel assembly (not shown) which would be placedadjacent a second end wall of greenhouse 12 and would be similar instructure and operation to reel 44. Actuation of the deployment reelassembly would cause cover 10 to be deployed in place, as seen in FIG.1, while actuation of the storage reel assembly 44 would store cover 10,thus permitting sunlight to pass through the transparent panels 14 tocontact the growing plants.

Turning now to FIG. 2, there may be seen an enlarged view of a portionof multiple layer insulation cover 10 in accordance with the presentinvention. As was discussed previously, cover 10 is formed by fourlayers 30, 32, 34 and 36 which are spaced by an air bladder 40. As maybe seen in FIG. 2, top and bottom layers 30 and 36, respectively ofcover 10 are coextensive with a portion of bladder 40. Upper and lowerintermediate layers 32 and 34 are secured to the outer periphery ofbladder 40 at spaced locations by any acceptable means or method such asstitching or an adhesive. Bladder 40 is formed of the same material asthe four spaced layers and may be suitably treated to retain air underpressure or may carry an air tight plastic inner liner (not shown). Thematerial used in the fabrication of the multiple layer insulation cover10 is, as was discussed previously, an aluminum foil secured to apolyester scrim. A suitable material is FOYLON and is available from theDuracote Corporation.

The top and bottom layers 30 and 36 and bladder 40 terminate, at theirouter edge in a generally T-shaped strip or element 50. Strip 50includes a top piece 52 and a leg 54 which cooperate to form the T. Asmay be seen in FIG. 2, strip 50 is disposed with its top 52 within thesupport pipe 42 and with leg 54 passing through an axial slot 56 in pipeor support track 42. This slot 56 may be angled downwardly withreference to a horizontal plane thereby reducing wear on the undersideof leg 54 of T-strip 50. In a preferred embodiment in which the spanbetween side walls 20 and 22 is approximately 24 feet, the slot 56 maybe angled downwardly at approximately 9°.

Support 42 is shown in the preferred embodiment as PVC piping and thisis preferred since it is lightweight, durable, impervious to moisture,and the like, easily installed, and not particularly expensive. It willbe understood that other materials could be used for support 42 ifnecessary. Support 42 is secured to the spaced uprights 16 by anysuitable means such as brackets 58 which are held in place by screws 60or the like.

A cable 64 such as wire rope or the like is secured to a leading edgeportion 66 of T-strip 50 by a suitable U-shaped connector 68. Cable 64runs through the support tube 42 and is secured to the deployment reel(not shown). Actuation of the deployment reel causes the cable 64 topull the cover off the storage reel 44. It will be understood that asimilar cable would be provided in the other support tube secured to theother side wall of greenhouse 10 and that additional cables could besecured at spaced points across the leading edge of the multiple layerinsulation cover. It will also be understood that the leading edges oflayers 30, 32, 34, and 36 and of bladders 38 and 40 are all sealedtogether.

As the cables 64 are wound on the deployment reel, the multiple layerinsulation cover 10 is pulled off storage reel 44 and is deployed abovethe growing area of greenhouse 12, as seen in FIG. 1 at a desired heightsufficient to allow access to the plants or benches 28. The leg portion54 of T-strip 50 passes through the slot 56 in the support pipe 42 andthe top portion 52 of strip 50 seals the slot 56 to form an effectiveair seal. As the cover 10 reaches the deployed portion, an air opening70 in the lower side of bladder 40 is placed over a corresponding outlet72 in an air conduit 74. Correspondingly shaped, magnetized flexiblegaskets 76 and 78 are provided with gasket 76 surrounding air opening 70in bladder 40 and with gasket 78 being secured about outlet 72 of airconduit 74. Air is provided by a blower or fan (not shown) and isdirected up conduit 74 in the direction indicated by arrow A in FIG. 2.This air flow is sufficient to inflate bladder 40 to a shape as shown inFIGS. 1 and 2. It will be understood that the bladder along the otherlongitudinal edge of cover 10 is being concurrently inflated to deploythe cover with the four layers generally uniformly spaced.

Once multiple layer insulation cover 10 is deployed and the bladders 38and 40 are inflated, there is provided an effective means for retainingheat in the greenhouse. The four layers 30, 32, 34, and 36 are assembledin cover 10 with the reflective side facing upwardly. The air spacesbetween layers stop conductive heat loss, the air spaces are still sothere is little convective heat loss and the aluminum foil is a pooremitter of heat so there is little radiant heat loss. With the cover 10deployed, the heat remains in the greenhouse. There is little heat lossdue to poor sealing since the T-strip 50 and support tube 42 form aneffective seal. As may be seen in FIG. 2, the spaces between theuprights 16, transparent panels 14 and support tube 42 can be sealed bysuitable strips 80 of insulation such as expanded foam which arepermanently secured in place. Suitable means such as suspended drapes orflaps can be provided along the end walls of the greenhouse to preventescape of heated air around the reels.

In a preferred embodiment, in which the width of the greenhouse is 24feet, the air bladders 38 and 40 are structured to have a circumferenceof approximately 30 inches. Top and bottom layers 30 and 36 are incontact with bladder 40 each for approximately 14 inches and theintermediate layers 32 and 34 are spaced 2 inches from each other. Thisresults in a multiple layer insulation cover in which each layer isspaced approximately 2 inches from the next layer. The air supplied tobladders 38 and 40 is only slightly above atmospheric pressure byapproximately 0.6 inches of water. A small fan capacity is required anda fan which provides 50 CFM and draws only 50 watts of power will beadequate to inflate a bladder in several minutes. Since the layers ofcover 10 are very light, the force of each layer on the bladder is smalland would be in the order of 0.089 Lb/in over a 24 foot span with a 12inch sag at the center of the span. By suitable analysis, the length ofmaterial to be used to form the four layers can be selected prior toassembly so that the spacing will remain uniform across the entire span.It will be understood that the use of bladders 38 and 40, the airpressure required, and the amount of sag across the span can be varieddepending on the size of the span. It will also be understood that thesize of the fans can be varied depending on how rapidly it is desired toinflate the bladders. Additionally, plural fans can be placed along thelength of each bladder. Since these fans draw little power, they will beleft on when the cover is deployed thereby insuring inflation of thebladders and spacing of the layers even if there are minor air leaks.

When the cover 10 is to be stored, the fans are turned off and thestorage reel 44 is actuated to draw the cover 10 to the right, as seenin FIG. 1. The air is forced out of the bladders and the T-strips 50,which are made of nylon webbing or other similar material, aresufficiently flexible so that the top 52 folds adjacent the leg 54 oncethe T-strip is pulled out of the support 42 adjacent take-up reel 44.The rolling of the cover 10 in this fashion reduces wear to a minimumand stores the cover in as little space as possible.

The multiple layer insulation cover in accordance with the presentinvention as set forth hereinabove is an effective, economical, anddependable way of greatly reducing heat loss through the roof of agreenhouse or through any other poorly insulated area. The multiplelayers of the cover provide good insulation capabilities without bulkand with little storage space requirement. The longitudinally extendingair bladders facilitate the spacing of the layers in an effective andeconomical manner while not requiring large capacity fans or blowers.

While a preferred embodiment of a multiple layer insulation cover inaccordance with the present invention has been set forth hereinabove,fully and completely, it will be obvious to one of ordinary skill in theart that a number of changes in, for example, the number of layers, thetype of fabric, the drive means for the reels, the shape of the supporttubes, and the like, could be made without departing from the truespirit and scope of the invention and that the invention is to belimited only by the following claims:

We claim:
 1. A multiple layer insulation cover for preventing heatlosses from the interior of a building, said cover comprising:a. fourlayers of flexible cloth backed metal foil; b. first and secondelongated air bladders in said cover spaced from each other andextending along longitudinal edges of said cover, said layers of saidcover being spaced apart from each other by inflation of said bladders;c. support tubes extending along the interior of the building, saidtubes including axially extending slots and supporting said cover assaid cover is deployed in said building; d. T-shaped strips secured toouter edge portions of said cover adjacent said air bladders, saidT-shaped strips cooperating with said support tubes to support saidcover; e. means for inflating said air bladders when said cover isdeployed to space said layers; and f. means to move said cover betweendeployed and storage positions.
 2. A multiple layer insulation coveradapted for use in preventing escape of heat from the interior of abuilding, said cover comprising:at least three spaced, flexible layersjoined together along first and second spaced, parallel edge portions toform said cover, said cover extending transversely across the interiorof the building, spaced from, and generally parallel to, a floor portionof the building; first and second elongated air bladders in said cover,said bladders being secured in said cover adjacent said first and secondedge portions of said cover, respectively and being inflatable to spacesaid layers of said cover; means for maintaining said spaced layers ofsaid cover at a uniform distance from each other while allowing saidcover to sag transversely; support means securing said edge portions ofsaid cover to side walls of the building, said support means includingaxial slots through which said edge portions extend, said support meansbeing mounted so that said axial slots are angled downwardly withrespect to the floor of the building; and means for slidably securingsaid edges in said support means.
 3. The cover of claim 2 wherein saidsupport means are tubes, said tubes being secured to said building. 4.The cover of claim 2 wherein said means for slidably securing said edgeportions in said support means are T-shaped strips secured to edgeportions of said cover, a head portion of each said T-shaped strip beingcarried in said support means and a leg portion of each said T-shapedstrip extending through said axial slot and being secured to said cover.5. The cover of claim 4 further including means to deploy and store saidcover.
 6. The cover of claim 5 wherein said means to deploy and storesaid cover are spaced reels, said cover being movable between stored anddeployed positions by actuation of said reels.
 7. The cover of claim 6wherein said T-shaped strips are flexible, said head portion foldinginto coincidence with said leg portion during storage of said cover.